Hydraulic roof supports



July 27, 1965 Fil'ed March 19. 1963 HYDRAULIC ROOF SUPPORTS F. cowLlsHAw 3,197,168

2 Sheets-snee?l l "IIA '....VI'IIMH' July 27, 1965 F. cowLlsHAw 3,197,168

l HYDRAULIC ROOF SUPPORTS Filed March 19, 1965 2 Sheets-Sheet 2 United States Patent O" 3 1i claims. ici. 24a-sse) This invention is for :improvements in or relating to hydraulic roof supports primarily of the type used for long wall mining Where the supports are progressively advanced hydraulically.

It is of paramount importance for the hydraulic pressures to -be mtaintained at all operative times, and this .is dependent to a great extent on the eiciency of valves particularly in respect of their seatings which are included in a hydraulic circuit for control of the supports.

However in many instances the valves )are enclosed in parts of the support and leakage which may occur is not accompanied by external leakage which would be visible.

It has been proposed to provide means for indicating such leakage by use of a normal type pressure gauge disposed at a suitable visible location and connected into the hydraulic Acircuit lthereby to indicate fall in pressure which may be due to an internal leaky valve. But these pressure gauges are not entirely satisfactory for this purpose as they are unsuitable to be subjected to sudden release of high pressure (which may be in the region of 11,000 lbs. per square inch at a maximum and zero pressure minimum) which occurs when the support is released from the roof.

An lobject of the invention is -to provide in or for a hydraulic roof support, a hydraulic pressure indicator device of such improved construction as to be satisfactory in use.

The invent-ion provides in or for a hydraulic roof support, a hydraulic pressure indicator device in which telescopically mounted components are controlled for Arelative movement in one direction by spring means and in the other direction by the hydraulic pressure such that the rela-tive positions of the two members in their extension or contraction is indicative of .any pressure variation in the hydraulic system. Conveniently the telescopic components house a coil spring and one of them has a central spindle extending through `a hydraulic pressure chamber carried by the other component, the said spindle al-so having an inlet duct for communication fof iluid in the hydraulic circ-uit with said pressure chamber, and said spindle also having different diameter lareas whereby variation in hydraulic pressure causes movement of the pressure chamber along the spindle and consequential movement .of the pressure chambers telescopic component relatively to the spindles telescopic component.

The inner telescopic component conveniently carries the pressure chamber yand is calibrated by grooves and/or it may have indicator coloured bands.

The foregoing yand other features of the invention set out in the appended claims are incorporated in the specic embodiment which will Ibe hereinafter particularly described in ygreater detail by way of example with reference to the drawings in which:

FIGURE 1 is a cross sectional view of a hydraulic pressure indicating device according 'to the invention.

FIGURE 2 is a general side view of a hydraulic roof support embodying said device.

FIGURE 3 is `a diagrammatic view showing applications of the device to a warning system.

FIGURE 4 is a diagrammatic view showing applications of the device to a control for the hydraulic system.

Referring to lthe drawing, FIGURE l, the hydraulic pressure indicating device comprises ltwo telescopically lhll Patented July 27, 1955 ICC arranged 'components i.e. an inner hollow component 1 and an outer hollow component 2 Which house a coil spring 3.

The inner component l has a :flanged end la .against which one end of the spring `3 abuts .and secured to this lian-ge there is a ilange 4a of a member 4 extending interiorly :of the spring 3 for about half its length and being hollow to provide a hydraulic pressure chamber 4b. The opposite end of the other component 2 has a flange 2a to which is secured a `collar 5 on a spindle 6 which is secured to it by a nut 7 and washer 8, and which extends through the spring 3 and through the member 4 and its pressure chamber 4b to the other end of the device where it projects in the form of a screw threaded union 9 for screwing into a suitable part of the hydraulic circuit of the support.

rlhe union 9 has an inlet 9a leading to an axial duct 6a in the spindle 6, the duct extending through the spindle 6, for substantially the same length as the length of the hydraulic chamber 4b, to a blind end 6b from which there extends a transverse hole 6c leading into the hydraulic chamber 4b.

A spindle portion 6d of the spindle 6 at one side of the hole 6c is of larger diameter than a spindle portion 6e o-f the spindle 6 at the other side of the 'hole 6c, the two diderent diameter pants `6d and 6e being joined by an inclined annular portion df.

The hydraulic pressure chamber 4b is sealed against leakage along the spindle 6 by O rings il@ yand ll.

The inner component 1 is calibrated by grooves such `as indicated at ll2 and/or which may have different coloured bands.

The coil spr-ing 3 is constructed to have a rate of loading per inch of deflection which is equal in resistance to the hydraulic pressure multiplied by the diilerence in cross sectional area between the different diameter portions dd and 6e of the yspindle 6.

In operation of the device, the deilection of the spring 3, caused by variations in pressure of the hydraulic iluid act-ing in the hydraulic pressure chamber 4b between .the member 4 and the spindle 6, causes inward and outward movement of the inner component 1 relatively to the *outer component 2 thereby to indicate, by the position of the grooves .l2 in relation to the outer component 2 and/or the coloured bands, any rises or falls in the hydraulic pressure in the support.

The device may be iitted at a suitable visible locati-on in a hydraulic roof support. For exam-ple, as .shown in FIGURE 2, the support may be .of the type comprising a pair of spaced hydraulic props h3, 13a on a common base 14 and having a roof bar l5, and a projecting roof canti-lever 'lo pivoted to the roof bar and controlled through a slipper member l1'7.

The device is iitted to the prop 13 to communicate with the interior of the prop and with .a fluid fee-d inlet '18, is read-ily detected by the consequent visible condition of the indicating device.

Since the inner component l carrying the ilange in varies its .position on the spindle 6 as the pressure varies according to lthe load on the support, this variation is readily detected by the consequent visible condition of the .indicating device.

It would be possible to take advantage of movements of the inner component .l by causing it to .actuate either 1a ywarning system of pressure vaiiation, or it could be arranged to operate a mechanical trip to control the hydraulic function of the support.

tFor example as shown in FIGURE 3 the inner component l -acts on an operating arm roller i9 of an electric switch Ztl which, when operated, closes an electric circuit to an electric warning lamp 2l.

In another example FIGURE 4, the inner component Y n .1 .acts on an operating arm roller 22 of a mechanical actuatoror duid control device 23 which is suitably connected inthe system so that when it is operated it Acontrois the hydraulic function of the support in any desired manner.

What l claim is:` e

1. Fluid pressure responsive means comprising, in combination, a iiuid inlet member having a passageway therethrough for the duid, Va 'chamber-forming Vmember in communication with said fluid inlet member, and means adapting said fluid inlet and chamber-forming `members to provide opposed walls of different cross sectional areas,

e ween which the fluid is directed from said passageway, to cause relatively variable movements between said uid inlet and chamber-'forming members according to variable pressures of the fluid.

2. Means as claimed in claim 1 having a signalling device operable'by said movements between said fluid inlet and chamber-forming members.

3. Means according to claim 1 having a signal-operating'switch operated by said movement between said luid inlet and chamber-forming members.

d. Means as claimed in claim 1 having a `hydraulic system control device operable by said movement of said lluid inlet and chamber-forming members.V

S. Fluid pressure'responsive means comprising, in combination, a cylinder having two end diameters one smaller than the other, a spindle having two diameters one smaller than the other and extending through said cylinder, seals between said twovend diameters of said cylinder and said two diameters of said spindleV respectively, a iluid inlet extending through said spindle into said cylinder, two telescopicaily mounted sleeves one on the cylinder and the other kon the spindle, and a comparatively low rate springresistingany change in the fluid pressure, such change in pressure causing relative movement between the two telescopically mounted sleeves.

6. A lluid pressure indicating gauge comprising in combination, a fluid inlet member having a passageway therethrough for the lluid to be measured, a chamber-forming member in communication with said fluid inlet member, means adapting said lluid inlet and chamber-forming members to provide opposed walls of dilerent crosssectional areas, between which the fluid is directed from said passageway, to cause relatively variable movements between said fluid inlet and Vchamber-iorming members according to variable pressures of the uid, and position indicating means operable by said iluid inlet and chamber-forming members.

7. The lluid pressure indicating gauge of claim 6 wherein said chamber-forming member is a cylinder havingV annular end Walls of unequal cross-sectional areas, said fluid inlet member is a spindle having an outlet from said passageway to said chambergand said spindle comprises portions of unequal diameter at opposite sides of said outlet and slidably mounting said walls respectively.

S. The fluid pressure indicating gauge of claim d having end portions on said chamber-forming member, and sealing means between said iluid inlet member and said end portions.

9. The lluid pressure indicating gauge of claim 6 having inner and outer telescopically mounted components constitutingV said position-indicating means, means securing one of said components to said liuid inlet member, means securing the other of said components to said chamber-forming member, spring means biasing Vsaid components outwardly, and graduations on said inner component with which said outer component cooperates.

it?. A hydraulic mine roof support having an outlet communication with its pressure fluid, and secured to said outlet a iluid pressure-indicating gauge as claimed in claim 6.

Ztl. A fluid pressure-indicating gauge comprising, in combination, a spindle having a screw mounting end and an opposite screw end, a first bearing portion of one diameter extending from saidmounting end, a second bearing portion of smaller diameter extending between said lirst bearing portion and said opposite screw end, and a lluid passageway extending from said screw mounting end to between said irst and second bearing portions, a cylinder on said spindle with an annular chamber between them, and annular end walls of unequal crosssectional areas and incorporating end sealing bearings one on said first bearing portion and the other on said second bearing portion, inner and outer telescopically mounted indicating components disposed about said spindle and cylinder, means securing the inner component to said cylinder at said screw mounting end of the spindle, means for securing said outer component to said opposite screw end of said spindle, graduations on said inner component, and a coil spring disposed about said spindle and cylinderand interiorly of said components for imparting outward bias to the inner component and consequently to said cylinder relatively to said outer component.

References Cited by theExaminer UNlTED STATES PATENTS 1,915,122 6/33 Crowley 73-419 X 2,110,386 3/38 Williams 73-419 2,728,231 12/55 Blair 7.3-467 FOREIGN PATENTS 1,102,657 5/55 France.

574,822 4/ 33 Germany. 575,018 4/33 Germany.

75 2,056 11/56 Great Britain. 263,794 3/29 Italy.

CLAUDE A. LEROY, Primary Examiner. 

1. FLUID PRESSURE RESPONSIVE MEANS COMPRISING, IN COMBINATION, A FLUID INLET MEMBER HAVING A PASSAGEWAY THERETHROUGH FOR THE FLUID, A CHAMBER-FORMING MEMBER IN COMMUNICATION WITH SAID FLUID INLET MEMBER, AND MEANS ADAPTING SAID FLUID INLET AND CHAMBER-FORMING MEMBERS TO PROVIDE OPPOSED WALLS OF DIFFERENT CROSS SECTIONAL AREAS, BETWEEN WHICH THE FLUID IS DIRECTED FROM SAID PASSAGEWAY, TO CAUSE RELATIVELY VARIABLE MOVEMEBTS BETWEEN SAID FLUID INLET AND CHAMBER-FORMING MEMBERS ACCORDING TO VARIABLE PRESSURES OF THE FLUID. 